Jordan Morris, Julian Green and Matt Miazga were among the 23 players called into camp Saturday for the U-23 national team ahead of its two-game Olympic qualifying playoff with Colombia.

The first game will be played March 25 in Barranquilla, Colombia (2 p.m. PT, FS1, Univision Deportes) followed by a return leg March 29 at Toyota Stadium in Frisco, Texas. (6 p.m., ESPN2, UniMas).

Herzog's roster, which must be trimmed to 20 by Friday, features players from seven countries, including 11 from Major League Soccer. But just as noteworthy are some of the European-based players who were excluded; among them were defenders John Brooks, Cameron Carter-Vickers and DeAndre Yedlin; midfielders Christian Pulisic and Gedion Zelalem; and forward Rubio Rubin.

World Cup veterans Brooks and Yedlin are expected to be named to Juergen Klinsmann's senior team roster Sunday for World Cup qualifiers with Guatemala, which will be played on the same dates as the Olympic playoffs. Carter-Vickers was a late scratch because of injury, while Zelalem has not been playing regularly with his Scottish team, the Rangers.

Two of the players called up — midfielder Paul Arriola, which plays for Tijuana in Mexico's Liga MX and forward Mario Rodriguez of Germany's Borussia Monchengladbach — are products of the Galaxy's academy system.

Players selected still can participate in their club's games this weekend before reporting to Miami for a quick three-day training camp. Herzog can make changes to his roster after the first game.

The U.S., which has qualified for just one Olympic tournament since 2000, wound up in the playoff after failing to earn one of CONCACAF'S two automatic berths in the Rio Games in last fall's regional championship.

"We have to have two really good games with a lot of personality on the field that can deal with very tough, physical opponents," Herzog, speaking of the Colombia playoff, said in a statement. "We have to be prepared for everything."

Although both games will be played during a FIFA international break, professional clubs are not required to release players for a U-23 game as they are for senior team matches. But Herzog said the clubs he approached for players were cooperative.

"Everything was fine," he said. "The clubs, especially in MLS, did a good job sporting us because everyone knows that we have two very important games ahead of us."